Currently, laptop battery batteries use Thermal Cut Off (TCO) breakers, i.e., thermal fuses, for overtemperature/overcurrent protection. At a certain ambient temperature, when the charge-discharge current of the battery cell is greater than a set threshold value, the TCO breaker triggers protection and disconnects the battery cell, i.e., because the heat accumulation of the TCO breaker exceeds the threshold value and results in a bimetallic reversal bounce. When the TCO temperature drops below a certain temperature, the TCO breaker is closed. The TCO breaker functions as the overtemperature/overcurrent protection of the battery overcurrent. At a low temperature, the TCO breaker allows relatively high charge-discharge current. At a high temperature, the TCO breaker allows relatively low charge-discharge current. Thus, safety issues of battery cells caused by high charge-discharge at a high temperature can be avoided.
However, the current TCO breaker for overtemperature/overcurrent protection has following issues. For example, the TCO module to implement a TCO breaker is costly, and the TCO module (containing a TCO body and a welded nickel piece) can cause high power consumption due to its own high impedance during the charge-discharge process. Further, affected by the heat generated by the TCO module, the accuracy of the temperature/current protection can be poor, which seriously affects the battery discharge performance.